1. Technical Field
Various exemplary embodiments relate to a semiconductor device and a method of operating the same, and more particularly, to a semiconductor device having a vertical channel and a method of operating the same.
2. Related Art
An increase in demand of cellular phones, portable memory devices and digital cameras are leading to an increase in demand of non-volatile memory devices that are used mainly as memory devices of these products. Among the non-volatile memory devices, NAND flash memory devices are widely used as data storage devices.
NAND flash memory devices may be classified into two-dimensional (2D) semiconductor devices in which strings are formed in a horizontal direction to a semiconductor substrate and three-dimensional (3D) semiconductor devices in which strings are formed in a vertical direction to a semiconductor substrate.
A 3D semiconductor device is designed to overcome physical limits in improving the degree of integration of a 2D semiconductor device. The 3D semiconductor device may include a plurality of strings that are formed in a vertical direction to a semiconductor substrate. Each of the strings may include a drain selection transistor, a plurality of memory cells and a source selection transistor that are coupled in series between a bit line and a source line.
In the 3D semiconductor device having the above configuration, threshold voltages of the memory cells, coupled adjacent to the drain selection transistor, may be changed by resistance around the source line during program and read operations, which may deteriorate the reliability of the 3D semiconductor device.